Implement server-side public mute-list filtering for push notifications

[danieldaquino]

There are two kinds of mutes on Nostr: Public mutes and private (encrypted) mutes.

Although push notifications from users in encrypted mute lists needs be done on the device itself, filtering of users on public mute lists can be done on the server side.

Acceptance criteria:

• Push notification server reads public mute lists and does not send push notifications from any publicly muted users

[danieldaquino]

Working on this one first (out of the ones listed in #2225) since it is the highest risk item for our new push notifications rollout plan.

[danieldaquino]

@alltheseas @jb55, I was able to get this working!

Sent a patch: https://groups.google.com/a/damus.io/g/patches/c/VkD0QccsrEM

@alltheseas I am thinking to jump into #1704 on Wednesday to keep push notifications evolving, but please feel free to recommend me another ticket if you know of a higher priority item to work on!

Overall, please let me know if you have any questions or concerns! Thank you!